Safeguard / Iron Will
Safeguard: Lee Sin rushes towards a target ally, shielding them both from damage. If a shield is broken, half the energy cost is returned. After using Safeguard, Lee Sin can cast Iron Will for the next 3 seconds.
Iron Will: Lee Sin's intense training allows him to thrive in battle. For 5 seconds, Lee Sin gains lifesteal, spell vamp, and armor.

Dragon's Rage (Ultimate)
Lee Sin performs a powerful roundhouse kick launching his target back, dealing physical damage to the target and any enemies they collide with. Enemies the target collides with are knocked into the air for a short duration.
Flurry (Passive)
After Lee Sin uses an ability, his next 2 basic attacks gain 50% Attack Speed and return 10 energy each.

Akali
Akali is no longer a ninja

Alistar
Pulverize now slams enemies into the ground instead of into the air
Headbutt has been changed to Rocket Grab
Alistar is now a ninja

Amumu
Amumu is now happy
Emumu skin has been replaced with Punkmumu

Annie
Annie has grown up and is now a teenager
Tibbers now wears armor

Blitzcrank
Blitzcrank now giggles whenever he uses Power Fist

Cassiopeia
Cassiopeia has been removed from the League following an incident involving a plane
We’re tired of all the Miss Fortuning snakes, on that Miss Fortuning plane

Cho’Gath
Cho’Gath now starts the game the same size as if he had 6 feasts
Feast still increases Cho’Gath’s size
Bushes can no longer stealth Cho’Gath

Corki
Valkyrie is now global
Gatling Gun now heals teammates as well as damaging enemies
Corki can now fly over obstacles without using Valkyrie

Dr. Mundo
Dr. Mundo decided that he enjoys the color blue
Dr. Mundo now has mana
None of his ability costs have changed

Fiddlesticks
Crowstorm now triggers Terrify on all enemies caught in the area of effect
Terrify’s Fear duration has been increased to 10 seconds at all ranks
Fiddlesticks has been removed from the League

Galio
Now shouts “DEMACIAAAAAAAAAAAAAAAAAA!” while channeling Idol of Durand

Gangplank
Gangplank’s model has been replaced with a targeting reticle
Gangplank now fights from his boat
Parrrley is now global
His VO has been reworked to be shouted from a distance and includes far more laughter

Gragas
Gragas is now sober

Garen
Courage has been removed and replaced with a new ability

New Ability – Plant Grass
Garen infects an area with grass seeds, causing additional brush to grow over the next 30 seconds. When brush is fully grown, it can be used by allies and enemies

Jax
Jax can no longer dodge
Jax’s lamppost has been deemed overpowered and replaced by a rocket launcher
All of Jax’s abilities are now ranged and blow things up
Jax can now dodge again

Nidalee
Age reduced by 10 years
Aspect of the Cougar has been renamed to Aspect of the Puma

Pantheon
Grand Skyfall has been renamed to the more appropriate: “Man Drop”

Sion
Sion has taken a sabbatical from the League to pursue a lifelong dream of teaching Kindergarten
He’ll be back

Sivir
Ricochet bounces now apply on-hit effects such as Tiamat and Madred’s Bloodrazor

Sona
Now requires skill to play

Teemo
Cuteness increased by 10%
Teemo may no longer be the target of hostile attacks or abilities

Tryndamere
Undying Rage has been renamed to Endless Rage
Endless Rage now has infinite duration

Zilean
Zilean can now travel back in time creating new realities and tangent universes in the process
Something has gone terribly wrong

Items:
New Item: Yordle Saddle. Any yordle champion can buy this new item to ride Cho'Gath.
Wriggle's Lantern: new unique passive: taunts nearby Jaxes (both enemy and allied)
Tiamat has been renamed to Tamat